The antimicrobial activity of ethanolic and aqueous extracts of propolis in the Huasteca Potosina, in Mexico was evaluated. Strains of Gram negative: Escherichia coli ,Salmonella typhi and Klebsiella pneumoniae , and Gram positive microorganisms: Staphylococcus aureus , Staphylococcus epidermidis and Streptococcus agalactiae, were used. The minimum bactericidal concentration (MBC) of each extract was determined by the tube dilution method. The ethanol extract was significantly more inhibitory than the aqueous (p = 0.05). The ethanol extract CMB was 0.93 mg mL-1 for Gram-positive and 7.5 mg mL-1 for Gram negative, in the aqueous extract was 20 mg mL-1 for Gram-positive and 30 mg mL-1 for Gram negative. The ethanol extracts have higher antibacterial activity compared with aqueous extracts, and antibacterial activity depends on its origin and on the bacterial species evaluated.